Collagen extracted from multiple species and various tissues including skin, bone, and tendon displays great conservation of primary structure. Collagen extracted from cartilage has been shown to have a different primary structure and to be composed of three identical polypeptide chains. This is in contrast to the two different kinds of chains in the previously isolated molecules. We have shown that controlled chemical digestion of insoluble human dermis with cyanogen bromide releases fragments expected from study of the extractable collagen and also fragments that must be derived from a genetically distinct molecule with still another primary structure. This project will involve the isolation of intact molecules of this new collagen, determinatiion of the chain composition of these molecules, cyanogen bromide digestion of the separated chains to permit detailed comparisons with previously described species of collagen, determination of the distribution of the new collagen both within the skin and among various organs, and initial approaches to determining the function of collagen heterogeneity in disease states as well as in maturation and aging.